The present invention relates to television signals. In particular, the present invention provides methods and apparatus for detecting a high definition television signal and re-encoding the high definition signal to create a standard definition television signal. More particularly, the invention involves re-encoding a copy of the high definition (HD) signal into a standard definition (SD) signal and combining both the original HD signal and the re-encoded SD signal into a multiplexed signal. The provision of both an SD signal and an HD signal in the multiplexed signal enables both SD and HD television receivers to receive content initially provided as a high definition signal. The re-encoding may be performed, for example, at a cable television system headend.
There are currently over six million digital television receivers in use that cannot receive a high definition television signal, such as a high definition MPEG2 data stream. No method currently exists to dynamically address the necessary resolution change at a cable television headend to enable an SD television receiver to receive HD signals.
It would be advantageous to provide a method and apparatus which re-encodes an HD signal into an SD signal for receipt by an SD digital receiver. It would be further advantageous to multiplex the re-encoded SD signal with the original HD signal so that the multiplexed signal could be broadcast without regard to the type of receiver that will be receiving the signal, thereby enabling backward compatibility between an HD data stream and SD receivers.
It would be even further advantageous to resolve conflicts in the protocol data of the HD and SD signals. It would be still further advantageous to enable a cable television system headend to support legacy SD equipment and new HD equipment using the same television signal feed. It would also be advantageous to provide for re-encoding only when necessary and with minimal impact to a subscriber or the television system when a channel transitions between HD and SD.
The methods and apparatus of the present invention provide the aforesaid and other advantages.
The present invention relates to methods and apparatus for detecting an HD television signal (e.g., a high definition MPEG2 data stream) and re-encoding the HD signal to create an SD television signal. In particular, the invention involves re-encoding a copy of the HD signal into an SD signal and combining both the original HD signal and the re-encoded SD signal into a multiplexed signal. The provision of both an SD signal and an HD signal in the multiplexed signal enables both SD television receivers and HD television receivers to receive content initially provided as a high definition signal. The re-encoding may be performed, for example, at a cable television system headend. The high definition television signal may contain one or more television services (channels).
The invention enables backward compatibility between a high definition data stream and standard definition receivers.
In a preferred embodiment of the invention, an incoming television signal is demodulated at a demodulator. The demodulated signal is split at a splitter into a first signal and a second signal, the first and second signals being substantially identical. A decoder determines whether the second signal is an HD signal and in the event that it is an HD signal, decodes it. The decoded HD signal is re-scaled at a re-scaler into SD signal format. The re-scaled HD signal is re-encoded at an encoder as an SD signal. A multiplexer multiplexes the re-scaled and re-encoded second signal with the first signal to create a multiplexed signal having two versions of the original signal, such that when the incoming television signal is an HD signal, the multiplexed signal will contain an HD version and an SD version of the incoming television signal.
The incoming television signal may contain one or more television services carried in an MPEG2 data stream or the like.
In an alternate embodiment, the protocol data may be extracted from at least one of the first signal and the second signal (e.g., by a processor in conjunction with the splitter). The extracted protocol data may be redefined to eliminate any conflicts between the protocol data of the first signal and the protocol data of the second signal. The redefined protocol data may then be inserted into the multiplexed data stream.
Where the second signal is an SD signal, no re-encoding will take place. The re-defined protocol data of the second signal may point to television services carried by the first signal and the second signal.
The protocol data may include source identifiers. In such an instance redefining the protocol data may include redefining the source identifiers.
The protocol data may comprise a Program Association Table (PAT) which provides correspondence between a program number and a program identifier (PID) of the signal. The protocol data may also comprise a Program Map Table (PMT) which provides mapping between the program number and program elements. Where the protocol data includes a PAT and a PMT, redefining the protocol data may include redefining the PAT and/or redefining the PMT.
The protocol data may comprise program service information protocol data (PSIP). The PSIP data may include source identifiers, program numbers, virtual channel tables, master guide tables, event information tables, extended text tables, and the like.
In an alternate embodiment, the multiplexed signal may be encrypted by an optional encryption device.